Hydraulic pumps



Sept. 16, 1958 E. L'. LANE 2,851,952

' HYDRAULIC PUMPS P Filed June 27, 1957 5 sheets-sheet 1 ATTORNEYS E. L.LANE HYDRAULIC PUMPS Sept. 16v, 1958 Filed June 27, 1957 5 Sheets-Sheet2 INVENTOR ATTORNEYS Sept. 16, 1958 E. L. LANE 2,851,952

HYDRAULIC PUMPS v Filed June 2v, 1957` 5 sheets-sheet s rIl IIA

6 INVENTOR (5w/mq. 55W, BY

ATTOR N E YS Sept. 16, 1958 E. 1 LANE 2,851,952

HYDRAULIC PUMPS v Filed June 27, 1957 5 Sheets-Sheet ATTOR NEYS Sept.16, 1958 E. l.. LANE Y HYDRAULIC PUMPS 5 Sheets-Sheet 5 Filed June 27,1957 ATroRNEYs United States Pate-nto a The object-ofthe invention isthe provision of an improved-constructional arrangementof variabledelivery hydraulic pump, of the type having aplurality of cylindersarrangedfin communicating pairs, whereby. it is. possible to obtainrahigh :operating -output "pressure Handhigh volumetric etiiciency, anoutput delivery infinitely variable -between zero and-'fullv capacity,and certain other valuable -advantages which will be apparent 'from thefollowing description.

According to the invention a variable vdeliveryhydraulic Apumpof thetype specified is characterised by an arrangefment whereby the pistonsvof each communicating pair of cylinders are respectively driven from acommon 'shaft i through -the -media of eccentrics the" sheaves whereofare `mounted -on the shaft'andconnected thereto byhelical splines `ofopposite hand, such' that'anaxial adjustment -of the shaft produces arelative angular `.displacement of the eccentrics and-consequentlya-va'riation ofithe volumetric output.

One embodiment-ofA theinvention, and certain minor y-rnodilicationsthereoaarel illustratedV in and are hereinafter describedwith-*reference to the accompanying dia- ^`grammatic drawings. EIn said`-drawings, Fig v1 `is a longitudinal section of `the'pump, Figs. 2 and`3 are respectively sections of the lines II-II and III-#III of `Fig. l,Fig. .4v is a sectionon `the line IV-IV of'Fig.'3,

Fig. 5 is a fragmentary elevation'jof'alternative,manual means foreffecting an axial adjustment of thedriving shaftfand Fig. 6 is asection on the line VI-VIof Fig.`5. Fig. 7 illustrates apparatus `forcontrolling the pump by hydraulic servo mechanism, and Fig. 8illustrates further alternative control means,.dcpending in lthis caseThe pump depicted in Figs. l1 to 4 comprises a' block 10 housing fiveequiangularly spaced connected pairs of cylinders 11, 12, each pairbeing'sealed by individual Apistons 13, 14'and furnished Awith a singleinlet valve` 15 and a single outlet valve'16,-both said valves being ofthe seated type. rThe output valves 16 communicate by means of anannular duct' 161 Vwith theL pump delivery routlet 162. The Acylindersare disposed radially about `an axially mounted driving shaft117 whichmay be coupled at 171 toanelectricmotor or otherprime mover 1(notshown), and having spl-ined thereon two eccentrics 18, 19 which arerespectively locatedoppositethe inner ends of the pistonsvl, 14, whichlatter are karranged to' bear against grooved reaction rings 20, '21mounted on the yeccentric sheaves by needle bearings 22,22,thefarrangement being such that the pistons are reciprocated intheircylinders `by the throw of the eccentrics. l Each eccentric is-preferably made as an extension of a tubular shaft.23, supported by apair of taper roller anti-friction bearings 24, 24.

The splines 25, whereby the eccentrics 18, 19 receive rotarymotionfromtheidriving shaft 17 at equal speeds are helical and of respectivelyopposite hand, and the arrangement is such that,the effect of imparting`an axial movement tothe driving.,shaft117 is toproduce a rotary movementof the ,eccentric ;18 relative to "the other 19; provision is made foran axial shaft-adjustment sufficient to move each eccentricsthrough'anangle 2,851,952 4"Patteinliced Sept. .16, 1958 .of so that theconditions may be varied from a relative disposition of the eccentricsof 180, in which the stroke ofthe pistons 13 exactly balances that ofthe v`,pistons14 andthe output delivery has a'zero value, to aneccentric settinglin which the pressure strokeof lthe pistons 13' and 14coincides and -the output delivery is accordingly at a maximum. Anyrelativesettingof the veccentrics between .these limits willprovide'a'proportional -delivery rate.

`'"lhe'inlet may be connected-to a 'reservoir'so 5that suction lift canbe obtained, and in such'an arrangement return springs will be requiredto maintainV thepistons13, 14 in operativecontact'with the' eccentrics`18, '19. Such an `arrangement may uhowever be vdisadvantageous 'andit'isconsidered preferable to 'supply hydraulic uidto lthe inletvalve 15by-,the gear-type `constant-.delivery feed purr-1p"`i1lustrated kat theright-hand end of Figp'l, 'a1id"in"Fig.` 3, which-'comprises a lgearV26iixed onthe 4"shaft "171, 'atgear 27 meshing with the gear'26 andAarranged'to pumpdiquid'en'tering thegear chamber 28 'at `29throughthe'duct 30 by ythe 'passage 31 into" the fannularheader duct 32,whence the liquid has access to* the inlet valves 15. *By these meansthe useof'return springs4 for they pistons is rendered unnecessary,'whilst cavita'tionv and' starvation offlow to theV variable'delivery-pump Vare avoided "and the resultant lhigh volumetric--iciencyfprolongs thet'working life of the valves. "The `inlet pressuremaybemaintained byv employing a feed *pump havinga volumetric outputgreater Vthan the maxi- 'mumow through the variable delivery pump, andpassing the surplus feed to exhaust at 33 (Fig.` 3). Conveniently, theinleti'header Ai32 may be provided-with a'relief valve lof fthe4balanced `type offering a I constant ihydraulic nresistance atz'varying' rates of flow, such resistance `being determined'-by-externalmeans-f adjustment. fBy 'this ar-rangement -aback pressure Iismaintained in the -inlet 'header32. i

In Acasefthe driving shaft i7, being relatively unstable, "should-'tendto amplifysundesirable vibration forces `due toexcessive workingclearances in the transmission-fiele- `ments- (caused erg. by wear orinaccuracies- -in manufac- A-tur`e),itfrnay'be desirable to attach tothe-end of'a vcylin'dricalextension -34 of said-shaft17 the-pistonrod"L35 and pistonf36 of an' oil-filled double-acting dash-pot37.Asupply'of oil is led from the header l32 through Vthe passage 33 and apipe 39 to either side of the dash-pot piston*36,an'd the dash-potcylinder is` maintained `filled vvwith oil by-check-valvesll), "41whenthe pump is at rest, lthe-piston' lbeing-in hydraulic balance and airbeing exclude'd notwithstanding possible 'oil-leakage.

Whenltne -axialzpo'sition of the shaft 17 is such'asto *provide `a givenoutput delivery, the vcentripetal forces acting-through eacheccentric18,119 react axiallywi'thin the shaft, which is. therefore substantially-in'iequilibr-ium.

' YAny out-f-balance force tending to displace the-shaft axially y-m-ustovercome the resistance in-either direction 'f'fspringebiassed valves42, #i3 of small yoriiicefwhich flareprovide'd' inthe'dash-'p'otpiston-36. Thus, each such 1-vlve'42,='43will subject the oil in 'thedashpot to ay unit fpressurewhieh,multiplied by the annulararea-aroundf'the fpi'stonero'd 35, willl resist axial `movement of thelshaft: 17.

'fThe'shft 17. is operated for control purposesr by ymeans Rois-alevera44riarrangedto rotate a-r pinion 45 meshingwith la rack-246 'onfthe shaft-extension V34 and acting through thrustlbea'ringsl147,548.Suchform of control means'has a high lmeohanical'-advantage capable ofovercoming'the re'sistancefof the dashpot valves 42, 43 Aand therebyenables control to be effected manually Awithout `undue lelo'rt.

=-An"alte1nativefdevce for operating the lhelicalshaft17 i'for:zcontrolpurposes is Vshown in Figs. 5 vand l6. -In'this .:case1a11=gearquadrant-549 securedto Van'extension v-of the pinion 45 is rotated by aworm 50 and handwheel 51. Stops may be fitted to bear against thequadrant 49 and limit its movement. With this arrangement the dashpotassembly 35, 36, 37 may be dispensed with.

Which ever of the aforedescribed means for axial adjustment of the shaft17 is employed, the effect of such adjustment is to alter the phaserelationship of the eccentrics 18, 19 and therefore of the pistons 13,14, with the result that the volumetric output of the pump is regulatedaccordingly.

The radial pumping action of the pistons 13, 14 at high pressure, andthe consequent reaction of the liquid upon the helical splines 25, 25,are resisted by the combined axial and journal anti-friction bearings24, 24. This arrangement enables advantage to be taken of thecentrifugal pumping characteristics of taper roller bearings which areused in this situation, as illustrated in Fig. l. A small volume of thesurplus oil from the feed pump is tapped from the header 32 and meteredthrough the passages 52 controlled by the needle-valve 53 (Fig. 4) tothe chamber 54 containing the bearings 24 and eccentrics 18, 19. Saidpassages 52 feed oil between the taper roller bearings 24 whichcirculate oil to the innermost bearing 55 of the feed pump, the thrustbearings 47, 48, and most important, to the eccentrics 18, 19 and theirneedleroller supported reaction rings 20, 21. This llow is drained toexhaust through passages 56, 56 in which are provided light check-valves57, 57 which keep the pressure in the transmission chamber 54 slightlyabove atmosphere to exclude air and ensure the regular replacement ofoil, thus maintaining its lubricity.

It is a particular advantage of the present pump construction that itlends itself, due to the rectilinear characteristics of the controlelement and to the fact that the helically-splined shaft 17 ismaintained in equilibrium whilst transmitting considerable power, toremote control by suitable pneumatic, electric, hydraulic and mechanicalmedia, without locking the element.` Thus, in the embodiment illustratedin Fig. 7, there is a manuallyoperable control valve 58 arranged to feedsurplus oil fed from the header 32 via the pipe 59 to a double-actinghydraulic ram 6%) which is axially attached to a rack member 61 meshingwith a quadrant 62 operably associated with the pinion 45 by which therack 46 on the extension 34 of the driving shaft 17 is adjusted. As willbe evident from Fig. 1, the position of the control valve 58 will beeffective to select the direction of movement of the ram 60 andtherefore the direction of adjustment of the shaft 17.

Fig. 8 illustrates means by which the rate of delivery of the pump maybe controlled. The pinion 45 is connected to a quadrant 63 which mesheswith a slidably mounted rod 64 which latter is biassed to a positioncorresponding to preset or full delivery by a spring 65 compressedbetween the housing 66 and a collar 67 on said rod 64. On increase ofoutput pressure in the delivery outlet 162, such pressure is made toact, through the pipe 68 upon a single-acting ram constituted by the endof the dashpot piston rod 35 (for its equivalent), in opposition to theforce exerted by the spring 65, and on overcoming the latter, to movethe shaft 17 to a position of zero, or reduced, delivery. A usefulfeature of this control arrangement is that should oil escape from thepressurised system during such high-pressure period, the resulting dropin delivery pressure will cause the spring-biassed driving shaft 17 tomove and enable the pump to make up losses and restore the desiredpressure. The position of the rod 64 may be preset by adjusting theknurled nuts 69, 69 on the screw-threaded extension 70 of said rod.

What I claim as my invention and desire to secure by Letters Patent is:

l. A variable delivery hydraulic pump comprising a plurality ofcylinders arranged in communicating pairs, means for supplying liquid toeach pair of cylinders, an exhaust valve for each pair of cylinders, adriving-shaft,

a piston in each cylinder, there being on said driving-shaft in respectof each pair of cylinders two eccentric sheaves each in helicallysplined relationship with the shaft, each piston being arranged to bearagainst the periphery of one such sheave, means for shifting said shaftaxially in relation to the sheaves for producing relative rotationthereof, and means for damping axial displacement of said shaft in bothdirections, said damping means including a dash-pot, a double-actingpiston in said dash-pot and attached to said shaft for axial movementtherewith, a port at each end of the dash-pot, means supplying lowpressure liquid to said ports, two ducts through the piston forconnecting the compartments of the dash-pot on opposite sides of thepiston, and in each such duct a singleacting self-seating valve forrestricting ow of fluid through the duct, said valves being arranged tooperate in `opposite direction.

2. A variable delivery hydraulic pump comprising a plurality of pumpingunits, each said unit including two inter-communicating cylinders, adriving-shaft, said units being equiangularly assembled about saiddriving-shaft radially thereof, a header, means for supplying liquid tosaid header, inlet-valves respectively connecting the header with saidunits, an exhaust valve in each unit, a piston in each cylinder, therebeing on said driving-shaft in respect of each assembly of units twoeccentric sheaves each in helically splined relationship with the shaft,each piston being arranged to bear against the periphery of one suchsheave, means for shifting said shaft axially in relation to the sheavesfor producing relative rotation thereof, and dash-pot means for dampingaxial displacement of said shaft in both directions, said damping meansincluding a dash-pot, a double-acting piston in said dashpot andattached to said shaft for axial movement therewith, a port at each endof the dash-pot, means supplying l low pressure fluid to said ports, twoducts through the piston for connecting the compartments of thedash-pots on opposite sides of the piston, in each such duct asingleactingA self-seating valve for restricting ilowy of fluid throughthe duct, said valves being arranged to operate in opposite directions.

3. A variable delivery hydraulic pump comprising a plurality ofcylinders arranged in communicating pairs, means for supplying liquid toeach pair of cylinders, an exhaust valve for each pair of cylinders, adriving-shaft, a piston in each cylinder, there being on saiddriving-shaft in respect of each pair of cylinders two eccentric sheaveseach in helically splined relationship with the shaft, each piston beingarranged to bear against the periphery of one such sheave, taper rollerbearings supporting said shaft, means supplying lubricant fluid to saidbearings, the arrangement of said bearings being such that saidlubricant is delivered thereby to working parts of the pump, means forshifting said shaft axially in relation to the sheaves for producingrelative rotation thereof, and means for damping axial displacement ofsaid shaft in both directions, said damping means including a dashpot, adouble-acting piston in said dash-pot and attached to said shaft foraxial movement therewith, a port at each end of the dash-pot, meanssupplying low pressure liquid to said ports, two ducts through thepiston for connectlng the compartments of the dash-pot on opposite sidesof the piston, and in each such duct a single-acting self-seating valvefor restricting flow of fluid through the duct, said valves beingarranged to operate in opposite direction.

References Cited in the file of this patent UNITED STATES PATENTS886,047 Flinn Apr. 28, 1908 1,719,693 Ernst `luly 2, 1929 2,172,103Kotaki Sept. 5, 1939 2,327,787 Heintz Aug. 24, 1943 2,605,707 WorlidgeAug. 5, 1952 2,642,804 Bowers June 23, 1953

